feat: v2.6.0 — Chat UI composer (+ menu, project files, activity panel, permission mode, Stop), git on a workspace's extra folders (#70), long paste as a file (#68), S3 server mode (experimental)

Chat UI:
- Each Claude/Codex session keeps its own chat/terminal view; Settings only
  sets how new sessions open.
- Composer + menu: upload, project files and folders (#54, also dragged from
  the Files/Changes tree), context files, recent uploads, skills, plugins.
- Activity side panel (progress, outputs, files read, uploads, memory,
  skills, connectors) with a file preview; edited-file counts per turn.
- Permission-mode chip (Shift+Tab steps, read back from the pane:
  server/lib/pane-mode.js, GET|POST /api/run/:id/permission-mode).
- Stop (Esc) while the main agent works; the status is checked per agent
  (with session_id /api/agents ignores its status filter) and re-read every
  5 s while Stop shows.
- Dropped images shown in the conversation (GET /api/run/drop/:name, the
  requester's own drop dir), full-size viewer.
- A plain-text paste over 5,000 characters is attached as pasted-text.txt,
  so no prompt reaches tmux/argv limits (#68).

Changes panel: every /api/lanes/:id/git* route takes ?source=<lane_sources
id> (sourceFolder; ENOSOURCE otherwise) and a folder picker switches the
whole panel to a workspace's extra folder (#70).

Server mode S3 (one Linux user per account) — experimental, verified with
fake sudo plus a P6 managed-settings spike on a test account:
- member tmux listing runs in the background (cached, 15 s => unknown);
- transcript snapshot copy is async, chunked, temp file + rename;
- Express Layer patch only on Express 4;
- tmux capturePane/sendKey go to the member's own server.

Docs: the multi-user design moved in as docs/plans/server-mode/README.md
(the AgentHub-Server repo is gone); S3-PLAN P6 result; LANES/API/openapi.

client/src/components/conversation/ConversationView.tsx

@@ -5,7 +5,11 @@
  * the message stream via MessageList. Combines a WebSocket subscription, a
  * visibility-gated polling fallback, and a manual refresh button so the view
  * stays caught up even when hooks miss frames or the user is mid-text-only
- * turn (no PreToolUse fires until Stop).
+ * turn (no PreToolUse fires until Stop). The view sticks to its end while
+ * the reader is there: anything that makes it taller — a new line, the live
+ * step, an image loading, the pane shown again after being hidden by CSS
+ * (a `display:none` pane cannot scroll) — keeps the newest in sight, until the
+ * reader scrolls up; `follow` (a chat's send) sends it back to the end.
  * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
  */
 /* =============================================================================
@@ -79,12 +83,21 @@ interface ConversationViewProps {
   /** Fill the parent as a chat (a workspace's session view): no toolbar, no
    *  page-height cap — the parent sizes it and puts a composer under it. */
   fill?: boolean;
+  /** Opens a file named in a turn's "Edited N files" card. */
+  onOpenFile?: (path: string) => void;
+  /** The session runs in a pane: show the step in progress. */
+  live?: boolean;
+  /** Changed (a chat's send): back to the end, and stick to it. */
+  follow?: number;
 }
 
 export function ConversationView({
   sessionId,
   initialTranscriptId,
   fill = false,
+  onOpenFile,
+  live = false,
+  follow = 0,
 }: ConversationViewProps) {
   const { t } = useTranslation("sessions");
   const [messages, setMessages] = useState<TranscriptMessage[]>([]);
@@ -105,6 +118,7 @@ export function ConversationView({
   const lastLineRef = useRef(0);
   const firstLineRef = useRef(0);
   const scrollContainerRef = useRef<HTMLDivElement>(null);
+  const contentRef = useRef<HTMLDivElement>(null);
   const isAtBottomRef = useRef(true);
   const fetchingRef = useRef(false);
   // When a fetch is in flight and a new trigger arrives (WS event, poll,
@@ -392,6 +406,30 @@ export function ConversationView({
     }
   }, [hasMore, loadingHistory, loadHistory]);
 
+  // Stick to the end while the reader is there. Scroll events say whether
+  // they are; a size change — of the content, or of the box itself when a
+  // hidden pane is shown — never fires one, so it is watched here.
+  useEffect(() => {
+    const container = scrollContainerRef.current;
+    const content = contentRef.current;
+    if (!container || !content || typeof ResizeObserver === "undefined") return;
+    const observer = new ResizeObserver(() => {
+      if (isAtBottomRef.current) container.scrollTop = container.scrollHeight;
+    });
+    observer.observe(container);
+    observer.observe(content);
+    return () => observer.disconnect();
+  }, []);
+
+  // The reader sent a message: show it, and what follows, as it lands.
+  useEffect(() => {
+    if (!follow) return;
+    isAtBottomRef.current = true;
+    setAwayFromEnd(false);
+    setShowNewMsg(false);
+    scrollToBottom();
+  }, [follow, scrollToBottom]);
+
   // Auto-scroll to bottom after initial load
   useEffect(() => {
     if (!loading && messages.length > 0) {
@@ -450,38 +488,42 @@ export function ConversationView({
       <div
         ref={scrollContainerRef}
         onScroll={handleScroll}
-        className="flex-1 overflow-y-auto"
+        className="flex-1 overflow-y-auto [scrollbar-gutter:stable]"
         style={fill ? { minHeight: 0 } : { maxHeight: "calc(100vh - 320px)", minHeight: 200 }}
       >
-        {/* History loading indicator */}
-        {loadingHistory && (
-          <div className="flex justify-center py-3">
-            <Loader2 className="w-4 h-4 text-fg-muted animate-spin" />
-            <span className="text-xs text-fg-muted ml-2">{t("conversation.loadingHistory")}</span>
-          </div>
-        )}
+        <div ref={contentRef}>
+          {/* History loading indicator */}
+          {loadingHistory && (
+            <div className="flex justify-center py-3">
+              <Loader2 className="w-4 h-4 text-fg-muted animate-spin" />
+              <span className="text-xs text-fg-muted ml-2">{t("conversation.loadingHistory")}</span>
+            </div>
+          )}
 
-        {/* Scroll-up for history hint */}
-        {hasMore && !loadingHistory && !loading && (
-          <div className="flex justify-center py-2">
-            <span className="text-[11px] text-fg-muted">↑ {t("conversation.scrollForOlder")}</span>
-          </div>
-        )}
+          {/* Scroll-up for history hint */}
+          {hasMore && !loadingHistory && !loading && (
+            <div className="flex justify-center py-2">
+              <span className="text-[11px] text-fg-muted">
+                ↑ {t("conversation.scrollForOlder")}
+              </span>
+            </div>
+          )}
 
-        {loading ? (
-          <div className="flex items-center justify-center py-12 text-fg-muted text-sm">
-            {t("conversation.loading")}
-          </div>
-        ) : messages.length === 0 ? (
-          <div className="mx-auto max-w-md py-12 text-center">
-            <p className="text-sm text-fg-secondary">{t("conversation.empty")}</p>
-            <p className="mt-2 text-xs leading-relaxed text-fg-muted">
-              {t("conversation.emptyBody")}
-            </p>
-          </div>
-        ) : (
-          <MessageList messages={messages} loading={false} />
-        )}
+          {loading ? (
+            <div className="flex items-center justify-center py-12 text-fg-muted text-sm">
+              {t("conversation.loading")}
+            </div>
+          ) : messages.length === 0 ? (
+            <div className="mx-auto max-w-md py-12 text-center">
+              <p className="text-sm text-fg-secondary">{t("conversation.empty")}</p>
+              <p className="mt-2 text-xs leading-relaxed text-fg-muted">
+                {t("conversation.emptyBody")}
+              </p>
+            </div>
+          ) : (
+            <MessageList messages={messages} loading={false} onOpenFile={onOpenFile} live={live} />
+          )}
+        </div>
       </div>
 
       {/* Claude Desktop's round "back to the end" button */}